The present invention concerns an apparatus for producing an aerosol jet, which is more particularly intended, by way of example, for an apparatus for analysis by spectroscopy. In an apparatus for analysing a solution by means of spectroscopy, the solution to be studied is firstly finely divided in the form of an aerosol, and then injected into a plasma flame such as of ionised argon, at a temperature of the order of 5000.degree. C. The aerosol is excited in the plasma and in turn emits radiation which is characteristic of the elements contained in the solution. This radiation is analysed in a conventional spectrometer.
Various means are known for putting the solution into a finely divided form, and in particular the use of ultrasonics to cause the liquid mass to be broken down into very fine droplets; the droplets can then be entrained in a gas flow towards the position of use thereof and in particular towards the plasma torch. In the conventional apparatuses in their present state, certain droplets which are being transported can come into contact with the walls of the duct; in the vicinity of the plasma torch, the walls are hot, which, in that region, causes the droplets to evaporate, and the salts contained therein are deposited. This gives rise to the danger of restricting the flow section of the duct, and even blocking the duct. However, this also has the even more serious consequence of leaving in the apparatus a `memory`, which gives rise to the danger of falsifying the following analysis result, for example by a part of the deposits formed in the course of previous analysis operations being dissolved in the new mist of a subsequent analysis operation. In order to avoid such interference phenomena, the conduits for carrying the aerosol into the flame would have to be rinsed or changed for each analysis operation, which is incompatible with the increasingly felt need for the capability of carrying out sequential analysis operations at high rates.